EDMONTON - Filmmaker James Cameron's passionate fight for the environment has flourished in Hollywood, but got its start in his childhood days amid the woods and waters of Ontario, a colleague said Wednesday.

"He talked about growing up in Canada, enjoying the nature there, the free-flowing rivers he used to swim in as a kid and how much he values the environment," said Christian Poirier of the environmental group Amazon Watch.

"That's one example he gave us about why he feels so passionately about this issue, as well as others like the oilsands. He feels there are alternatives that we need to highlight that don't wreck the environment."

Cameron, maker of such Hollywood blockbusters as "Titanic" and "Avatar," is expected to arrive Monday for a three-day visit centred around Alberta's sprawling oilsands operations.

He is set to meet with oil executives and local native leaders Tuesday and then head south for a meeting with Premier Ed Stelmach the next day in Edmonton.

Cameron's environmental advocacy has grown in lockstep with his skyrocketing fame and financial success. "Avatar" -- the story of a futuristic race of blue-skinned, indigenous people battling rapacious miners and their soil-destroying claw machines -- is an allegory about the cost of long-term ecological disaster for short-term profit. It has amassed close to US$3 billion in global ticket sales.

Earlier this year Cameron, 56, offered the technical expertise gleaned on such underwater movies as "Titanic" and "The Abyss" to try to help stop the Deepwater Horizon oil leak in the Gulf of Mexico.

He has spoken out against those who question the science of global warming. In March, he publicly challenged all such naysayers, announcing "I want to call those deniers out into the street at high noon and shoot it out with those boneheads."

He later went so far as to promise to publicly debate the issue with three naysayers at an event in Aspen, Col. His credibility took a hit when he backed out at the last minute.

His Alberta trip stemmed from public comments he made this spring while promoting the release of "Avatar." He called the oilsands -- with its strip-mine operations and great inland lakes of toxic waste -- a "black eye" on Canada's image as an enviro-leader.

That prompted Stelmach to invite Cameron to see the oilsands for himself, an offer Cameron accepted two weeks ago by letter to the premier's office.

The trip will resemble two tours Cameron made to a remote tributary of the Amazon River this spring, when he joined with Amazon Watch to try to stop the construction of a massive dam called Belo Monte.

Environmentalists say the dam on the Xingu River would dry up almost 100 kilometres of the river, flood hundreds of square kilometres of land around it and effectively destroy the indigenous groups nearby.

Cameron was accompanied by wife, actress Suzy Amis on both trips, said Poirier, who helped organize the tour and served as Cameron's interpreter. The second trip included actress Sigourney Weaver, who starred in "Avatar" and in an earlier Cameron movie "Aliens."

The indigenous leaders came from all over. They streaked Cameron's face with warrior paint. He put on a headdress, shook a spear and listened to their stories, comparing their plight to that of snake, according to a report from The New York Times.

"The snake kills by squeezing very slowly," Cameron was quoted telling the people in the Times story. "This is how the civilized world slowly, slowly pushes into the forest and takes away the world that used to be."

Poirier said his crew feared Cameron would be a high-maintenance Tinseltown "diva."

In Hollywood, Cameron admits he "eats pressure for breakfast" and is considered to be a hard-driven, hard-driving individual famous for sleeping four hours a night, and emasculating staff with profanity-laced emails and tirades. He butted heads with the British film crew on "Aliens," trying to work them overtime and deny them their tea breaks. Actress Kate Winslet said she chipped a bone, fell ill and almost drowned on the set of "Titanic." On "The Abyss," Cameron pushed the actors to save time by peeing into their wetsuits.

Poirier said the Cameron they worked with was "really down to earth," with a good sense of humour, happy to sit back and learn from the tribespeople. When their boat broke down, Cameron helped bail water.

He endured the punishing heat and humidity, long boat rides, bugs and sleeping in a hammock on the ship at night.

"He was eager to learn about people's stories," said Poirier.

"He's a sponge for information. As we gave him briefings on the impacts of the Belo Monte (dam) he was able to really digest and analyze the information in a way that was quite impressive.

And the media attention, he said, was unbelievable. Poirier said it had previously been a disappointing fight trying to get any coverage of the dam story.

When Cameron showed up, he said, news conferences that previously had attracted a couple of journalists, were now packed to the doorways with reporters and cameras.

"When he came on board the coverage exploded," he said. "For that we are very grateful."